The Pegasus XL rocket carried NASA's Interface Region Imaging Spectrograph (IRIS) spacecraft, built by Lockheed Martin, into a sun-synchronous polar orbit for continuous solar observations throughout the two-year mission. IRIS is designed to make detailed measurements of the flow of energy and plasma through the sun's atmosphere and heliosphere.

ATK is the major propulsion provider for the Pegasus XL rocket, delivering motors for all three stages of the Pegasus rocket. ATK's Orion motors have provided reliable propulsion for the Pegasus since its first mission in 1990. They are manufactured in Magna, Utah.

ATK also provided several structures and components from its Clearfield, Utah, facility for the Pegasus rocket. The three composite rocket motor cases were manufactured using ATK's advanced filament winding processes. Several other composite structures—including the interstage assembly that joins the 50-inch diameter second stage case to the 38-inch diameter third stage case, raceway covers used to protect flight critical cabling, and the fairing that encases the third stage motor and payload—were manufactured using hand lay-up processes. ATK also manufactured the flexseals that facilitate movement of the second and third stage nozzles.

For the IRIS mission, ATK manufactured the camera structure for the Smithsonian Astrophysical Observatory at its San Diego, Calif. facility.

The Pegasus rocket traveled under Orbital's L-1011 "Stargazer" carrier aircraft to an altitude of approximately 39,000 feet, where it was released horizontally before the first-stage Orion 50 SXL motor ignited. Approximately 130 seconds into the flight, the Orion 50 XL second-stage ignited and a composite payload fairing was jettisoned. After a several-minute coast period, the third-stage Orion 38 motor burned until approximately 10 minutes into the flight. Three minutes later, when the Pegasus released IRIS into its intended orbit.

This was the 42nd mission launched by Pegasus rockets. Pegasus, which has deployed over 80 satellites into orbit, has set the standard for reliable small launch vehicles using ATK's Orion motors.

Key partners supporting the manufacturing of ATK's Orion motors include Reinhold Industries and Votaw Precision Technologies, both located in Santa Fe Springs, Calif., and Central Valley Machine, in Logan, Utah. Reinhold provides the Pegasus nozzle assemblies, while Votaw provides the saddle assembly and Central Valley Machine provides the critical attach hardware. All of these suppliers are vital to the success of the Pegasus program.

ATK is an aerospace, defense, and commercial products company with operations in 21 states, Puerto Rico, and internationally. News and information can be found on the Internet at www.atk.com, on Facebook at www.facebook.com/atk, or on Twitter @ATK.